This invention relates to a method of assembling pneumatic tires such as automobile tires.
Of the pneumatic tires, the bias tire is produced by applying an inner liner, a carcass, a breaker and a tread, in the order mentioned, to a cylindrical building drum, deforming the resulting cylindrical green case into a toroidal form, and vulcanizing the assembly. Further, the radial tire is produced by applying an inner liner, a carcass and a sidewall, in the order mentioned, to the building drum of a primary building machine to form a cylindrical primary case, transferring said primary case to the building drum of a secondary building machine to deform it into a toroidal form, applying a belt and a tread thereto, and vulcanizing the resulting green case.
And, conventionally, both in the building of radial tires and in the primary and secondary building of radial tires, the strip-like members other than the tread, i.e., the inner liner, carcass, sidewall, breaker, belt and the like, after being produced in the form of long strips, are superposed on a liner and then, together with said liner, wound in the form of a roll and this roll is conveyed to a rear region of the servicer of the building machine, where it is then rotatably installed, whereupon the liner is separated as said strip-like members are withdrawn from the roll, so that only the long strip-like materials are placed on the transfer belt of the servicer in their straightened state as they are classified into the inner liner, carcass and so on, on which belt the strip-like members are cut into predetermined lengths, the latter being fed to said building drum.
Conventionally, since a long strip-like member is wound in roll form and cut into predetermined lengths on the servicer of the building machine and then fed to the building drum, the strip-like members develop curling sets due to winding during storage. Furthermore, the curling sets in the strip-like members differ in curvature between beginning and end of the winding. For this reason, when the strip-like member is placed in its straightened state on the flat transfer belt of the servicer and cut into predetermined lengths, errors in measurement of length occur; thus, it has been necessary to apply tension thereto to remedy said curling sets. Further, internal stresses due to bending and compression are applied to the strip-like members during storage. Since maid internal stresses increase toward the portions of the strip-like members disposed in the core, i.e., on the winding-start side, there has been a problem that the amounts of shrink of the lengths into which a strip-like member has been cut increase as the winding-start side is approached.
Further, when several kinds of strip-like members corresponding to a single lot are stored in roll form, the elongations produced differ from member to member. Therefore, when the formation of one lot is completed, the respective amounts of remnants of strip-like members vary, and hence the number of tires for one lot is limited by the shortest strip-like member. When the amounts of winding of said strip-like member are increased so as to avoid this problem, a new problem arises that the amounts of remnants of strip-like members increase.
Further, whereas the extruder and related devices for producing strip-like members including said inner liner and carcass have a production capacity corresponding to several tire building machines, the servicer of the tire building machine is equipped with several transfer belts corresponding to the several kinds of strip-like members and each transfer belt has a length measuring and cutting device for the strip-like member. When it is desired to automate the tire building operation, a device for guiding the front end of a strip-like member to the servicer has to be installed for each transfer belt, raising a problem that the installation cost increases.